There are several known methods to perceive depth. Examples are stereoscopic perception of depth, posychological perception of depth using visual cues and the use of changing focus to perceive depth. A viewer viewing a scene in which the focal point changes will perceive that the scene has depth.
Stereoscopic depth perception requires that the viewer views a scene from two different locations at the same time. In real life, this means that he sees the same scene using both his left eye and right eye to see different images. When two dimensional visual images are substituted for real life, it requires the use of two images taken from different right eye and left eye locations respectively.
On the other hand, a viewer can perceive depth by virtue of a number of psychological depth perception cues which are present in both real life and in two dimensional visual images. Common cues include effects where the change of coloring or softening of the shapes gives a feeling of distance to far objects, distribution of light and shade on an object, overlapping of contours as when a near object hides part of a more distant object, geornetrical perspective for example in the case of the converging of the parallel rails of a railroad track as they extend in the distance, movement of an object in a visual image either towards or away from the viewer or audience, and movement for stimulating the Pulfrich effect.
This is true of all the various devices in which two dimensional visual images are projected onto screens. Such devices include televisions, motion picture theaters, training simulators, multi-media systems and so on having applications in the areas of entertainment, work, education, exhibitions, training, etc.
A number of devices had been proposed to permit a viewer or an audience to view three dimensional visual images or at least the illusion of three-dimensional visual images when viewing two dimensional visual images. These fall into three groups: those which provide stereoscopic viewing, those which create the psychological illusion of depth and those. Display images on a three-dimensional display system, such as a surrounding screen.
Devices providing stereoscopic viewing generally require the projection of two pictures of the same view, taken simultaneously by more than one camera from slightly different angles, to emulate the binocular vision of normal eyes. Several examples are shown in U.S. Pat. No. 4,420,230 to MeElveen, U.S. Pat. No. 4,714,319 to Zeevi, and U.S. Pat. No. 5,225,881 to Marks. The use of a vibrating mirror or screen is shown in U.S. Pat. No. 4,130,832 to Sher and U.S. Pat. No. 3,814,513 to Nims et al. Other systems require special spectacles to be worn by the viewer or other devices which direct the proper view to the proper eye, All these systems are cumbersome and costly to use. Also, they tend to cause an uneasy feeling in the observer often resulting in headaches that may become severe. Thus these systems have failed to become popular.
The second approach is shown in U.S. Pat. No. 4,651,219 to Rickert, U.S. Pat. No. 3,582,961 to Shindo and U.S. Pat. No. 4,000,367 to Field wherein depth perception is provided by isolating the image to be viewed. In this way, the stereoscopic cues of the space surrounding the image are suppressed so the inherent psychological depth indicators in the picture can be sensed by the observer who perceives a two dimensional visual image as a three dimensional scene. Other devices which produce a similar result are described in U.S. Pat. No. 3,820,873 to Redington et al., U.S. Pat. No. 4,154,514 to Harvey which utilize a curved screen, and U.S. Pat. No. 4,941,041 to Kenyon which utilizes the Pulfrich illusion.
Other devices for providing three dimensional viewing are also described in the following U.S. Patents:
U.S. Pat. No. 2,468,046 to de los Monteros discloses an apparatus for projecting and viewing images with a depth effect through the use of at least one mirror to reflect the image from a projector onto a screen such that a degree of displacement between the images produces the illusion of stereoscopy.
U.S. Pat. No. 3,514,871 to Tucker discloses a wide angle visual display for a training simulator which eliminates distracting discontinuities found in many wide angle displays. It does so by providing three virtual image lenses between the viewing point and the two dimensional displays and by providing substantial duplication of the projected image on the marginal portions of the displays. This creates binocular vision at the comers of the displays which gives the illusion of three dimensionality.
U.S. Pat. No. 5,274,405 to Webster describes a device into which the head is placed wherein images are projected both to the area of visual attention and the area of peripheral vision of each eye, The images are focused on the screens to provide sharp stereoscopic viewing throughout the field of view.
Still another method which has gained some popularity is the so-called Imax system., of the IMAX Corporation, of 45 Charles street, East Toronto, Ontario, Canada. In this system, the images are taken simultaneously by several motion picture cameras rigidly to mounted together. The images thus acquired are then displayed in a properly fitted cinema theater with similarly configured projectors. The resulting three-dimensional motion picture gives the viewer a very realistic feeling that the action is actually taking place around him. Further, this system does not suffer from the drawbacks of stereoscopic viewing systems--the need for special glasses and the uncomfortable feeling.
However, this system does suffer from an important drawback. As anyone knowledgeable about cinema technology can easily appreciate, filming in a wide angle of view simultaneously (typically, the angle of view in these theaters is 150 degrees or more) is next to impossible in most circumstances--with the major exception of nature shots, scenery such as Niagara Falls filmed from the air and the like. Filming an actor engaged in action or even merely talking is next to impossible, and in any case extremely expensive, since all the lighting, recording and other equipment necessary for the shooting will also be filmed. Thus, this system has also failed to become popular, and there is only a relatively small number of cinemas and of films that were produced by this method.
Other methods for producing three-dimensional moving images are based on computer generated images. An example is U.S. Pat. No. 5,184,956 to Langlais et al., where computer generated data is used to produce a three-dimensional display for the purposes of driving training. It is easy to appreciate by any one skilled in this field that it is not difficult to adapt computer generated imaging techniques to many types of display systems such as stereoscopic display, wide angle display, and also three-dimensional display. This is so because the entire information required of each part of the image is known to the computer's program--including all the three-dimensional structure of each object, its surface color, texture, and so on. This seeming advantage is also the major disadvantage of such systems: the preparation of a realistic image requires painful and elaborate design of each and every detail. Thus the display is either non-realistic or else extremely expensive and laborious.
Today, no known method exists which can produce and display moving images that creates a realistic feeling of participation in the person viewing the display.
Thus there is a need for simple and economical methods for producing, preparing and displaying three dimensional moving images and stimulating the feeling of viewer participation in the displayed movie.